Chronic stress activates behavioral problems such as loss of pleasure and depression | Health

it’s clear Chronic anxiety It can affect our behavior, leading to problems like depression, decreased interest in things that once brought us joy, and even post-traumatic stress disorder.

Now scientists have evidence that a group of neurons in an arc-shaped part of the brain becomes overactive after chronic exposure to stress. When these POMC neurons become very active, this type of behavioral problems The result And when scientists reduce activity, so does behavior, they report in the journal Molecular Psychiatry.

Scientists at the Medical College of Georgia at Augusta University looked at the hypothalamus, which is key to functions such as secreting hormones and regulating hunger, thirst, mood, sex drive, and sleep, at a group of neurons called proopiomelanocortin, or POMC, neurons, in response. To 10 days of chronic, unpredictable stress. Unexpected chronic stress is used extensively to study the effect of exposure to stress in animal models, in this case including things like restraint, prolonged wet bedding in a tilted cage, and social isolation.

Also read: Mental health tips: 3 effective ways for women to cope with everyday stress

They found that stressors increased the spontaneous firing of these POMC neurons in male and female rats, says corresponding author Xin Yun Lu, MD, PhD, chair of the MCG Division of Neuroscience and Regenerative Medicine and Georgia Distinguished Researcher in Translational Neuroscience.

When they activated neurons directly, rather than letting stress increase their firing, it also led to a pronounced inability to feel pleasure, which is called anhedonia, and behavioral hopelessness, which is basically depression. In humans, indicators of anhedonia may include not interacting with good friends and loss of libido. In rats, their usual love for sugar water, and male rats, who usually like to sniff the urine of females when they are in heat, also lose some interest.

Conversely, when the MCG scientists inhibited neuronal firing, it reduced these types of stress-induced behavioral changes in both sexes.

The findings suggest that POMC neurons are both “necessary and sufficient” for increased susceptibility to stress, and their increased firing is a driver of consequent behavioral changes such as depression. In fact, stress overtly reduced inhibitory inputs to POMC neurons, says Lu.

POMC neurons are located in the arcuate nucleus, or ARC, of ​​the hypothalamus, an arc-shaped brain region already thought to be important for how chronic stress affects behavior.

The same region is occupied by another group of neurons, called AgRP neurons, that are important for resistance to chronic stress and depression, Lu and her team reported in Molecular Psychiatry in early 2021.

In the face of chronic stress, Lu’s lab reported that AgRP activation decreases along with behavioral changes such as anhedonia, and that when they stimulate those neurons, the behaviors decrease. Her team also wanted to find out what chronic stress was doing to POMC neurons.

AgRP neurons, known for their foraging role when we feel hungry, are known to have a yin-and-yang relationship with POMC neurons: when AgRP activation goes up, for example, POMC activation goes down.

“If you stimulate AgRP neurons, it can lead to immediate and powerful feedback,” says Lu. Food deprivation also increases the firing of these neurons. It is also known that when triggered by hunger signals, AgRP neurons send messages directly to POMC neurons to release the brakes upon feeding.

Their studies found that chronic stress disrupts the balance of yin and yang between these two groups of neurons. Although projecting AgRP onto POMC neurons is clearly important for firing activity, the intrinsic mechanism is probably the main mechanism underlying overactivation of POMC neurons by chronic stress, says Lu.

This story was published from the news agency feed without edits to the text. Only the address has changed.

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